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Aquifer Recharge on pace to match last year's record

IDAHO FALLS— The US Bureau of Reclamation told water users that they will keep Southeastern Idaho canals flowing this winter.

During normal years the Bureau has a requirement that Palisades Reservoir must shut down the canals for the winter to rebuild the water supply. But things are different this year because Upper Snake Reservoirs are nearly full after a record rainfall this year.

“I just checked and most of the state is at 145-percent of average precipitation. This is a good thing for recharge. It’s a good thing to get all that water back in the ground,” said Idaho farmer Danny Ferguson of Rigby.

Last years landmark winter left record snowpack and because of that, streamflows continue to run high. Water District 1 officials say that flows at the Heise gage north of Idaho Falls are the second highest in recorded history. The Idaho water year officially ended Sept. 30th, but last years snowpack will extend into next summer.

“I don’t see a downside to releasing this water at all,” said Ferguson who gets his water downstream from Palisades, “On the Harrison canal, we shut down for a couple of weeks but the canals are running again and all of the water is going into the aquifer.”

Under the Reclamation’s Winter Water Savings Program, Canal companies must close their canals for 150 consecutive days after the irrigation season, which allows the reservoirs to fill back up.

After last winter, The Department of Idaho Water Resources reported more than 315,000 acre-feet of water was recharged this past year in accordance with the state’s water right. Canal companies and irrigators recharged another 140,000 acre-feet. And pumpers are doing their part with an agreement to cut well irrigation by more than 240,000 acre-feet a year to help build the aquifer back up.

It all started exactly a year ago according to the National Weather Service. The fall of 2016 brought heavy rainstorms in Boise, Twin Falls, and Pocatello. The Snake River plain got almost 3 inches of precipitation, that's almost 2 inches more than normal with heavy snow and cold temperatures into May. The National Weather Service says we’ve had a nearly identical pattern so far this year.

That weather pattern has water managers already thinking where to put all of that water.  Water District 1 in Eastern Idaho reports their reservoirs have just a million acre-feet of available space, they usually have nearly twice that much storage space behind the dams.

The Bureau of Reclamation is acting proactively, they’re suspending the Winter Water Savings requirement for the next three months. The usual Palisades winter release is about 900 to 1,100 cubic feet per second. But so far this winter they’re releasing more than 3,000 cubic feet per second and could keep those flows well into March depending on snowpack.

“We need the measuring stick that last year provided us, we need to see the science and this release will show us what we’ve done over the past couple of years. It's exciting because these measurements will tell us what we’ve done and where we need to go in terms of restoring the aquifer,” said Ferguson.

The state has a special water right on the Lower Snake specifically for aquifer recharge. Recharge involves paying canal companies to run water through unlined canals or into spill basins where water seeps naturally into the aquifer and restores groundwater.

Wes Hipke, heads the Idaho Department of Water Resources recharge program and says they’ve already recharged 120,000-acre-feet, 61,000 acre-feet of that came from the Surface Water Coalition. The coalition received the water from junior groundwater users and food processing companies.

“We’re running water everywhere,” said Hipke. “Above Minidoka, Springfield, American Falls, Twin Falls Canal company, Southwest Irrigation District. There are at least 12 different entities taking part in this recharge effort.”

The Bureau’s announcement will enable some canal companies to continue recharging the storage water for the state in November when they’d normally restricted by Winter Water Savings.

“We’re off to an amazing start, normally we’d be at 20,000-acre-feet and currently we’re six times that,” said Hipke.

With winter weather the canals are starting to freeze up. That limits recharge but a warm fall kept the recharge going at a record pace. Still, even with snow and ice the Department of Water Resources expects to drop 600 to 700 cubic feet per second into the aquifer through the winter and hope to triple that in March depending on snowpack.

“My current numbers show at least 280,000-acre-feet for the current year. That doesn’t count the Little and Big Wood rivers, and the Upper Valley. There's a good chance we can do what we did last year, but that depends on Mother Nature, this is far beyond our expectations three years ago,” said Hipke.

The Recharge program is still making calls to find more recharge partners. They’re also speeding up releases in the Upper Valley to free up space in Palisade Reservoir.

Last month the National Weather Service declared that the Pacific Northwest was under the influence of the La Nina weather system.

“Right now in terms of precipitation, we’re 20 percent higher than last year at this time and well above normal. But that doesn’t mean much until January. That's when the weather patterns start diverging. But we’re in a really good place right now, we’ve had a wet Fall and were off to a great start, and the reservoirs started nearly full this water year that started in October,” said Hipke.

Idaho water officials have asked Congress to approve a permanent policy change that would make it easier for the Bureau to dispense with Winter Water Savings during wet years. Farmers are on board and look forward to restoring the aquifer.

“We’re going into this winter, wet,” said Ferguson who runs a large alfalfa operation outside of Rigby. “We have above average precipitation, I’m positive about this. Instead of flushing it out for fish, we’re doing something for the aquifer. We have so much water that we have to get rid of reservoir water just to hold off a normal year.”